Calories Explained: Everything You Should Know
Let’s take a quick moment to discuss calories. You often hear the term ‘calorie’ used to describe food and dietary intake, but may not fully appreciate what the term means and why we use it to when discussing foods.
A calorie is a unit of energy. That is to say that any foods and drinks you consume provide you with “energy” and we use calories as a way of measuring how much energy we are getting from any given source of food.
The technical definition is that a calorie is the amount of energy needed to raise 1 gram of water by 1 degree of celsius. This is how scientists would discuss calories in a laboratory setting or a textbook, but it’s not really a practical way to think about calories as your body uses them.
Although people often talk about “low calorie” diets or being in a caloric deficit, calories are actually essential to our survival. We require their energy to survive. Like most things, they become a problem when we consume too many (leading to obesity) or too few (leading to weight loss and potentially starvation).
You should think of calories as describing how much energy is in something that you are going to eat or drink. When you’re looking at the nutritional description, it will often say the number of calories in a single serving size. Keep in mind serving size varies dramatically from one product to another, so read closely.
There are a couple of things you should know about calories.
1. There are ‘calories’ which I have described above, and if you have 1000 of them, that is referred to as a kilocalorie (kilo means thousand in the metric system). Sometimes, calorie with a capital C will refer to kilocalorie, but this convention is not always followed. It can be very confusing but you should assume that calorie on any food packaging actually means kilocalorie.
2. You can actually define the number of calories in your macronutrients and use them to estimate the number of calories in a meal. They are as follows:
- 1 gram of carbohydrates contains 4 calories
- 1 gram of protein contains 4 calories
- 1 gram of fat contains 9 calories
- 1 gram of alcohol contains 7 calories
You can use this information to calculate the number of calories in a specific food item. On pre-made food products, it’s generally much easier to read the nutritional labeling.
3. The amount of calories a given person requires per day varies widely from person to person and will be the subject of a different discussion. In general, the average male requires 2,500-2,700 calories per day and the average female requires 2,000-2,200. Again, this is a very generalized statement and your individual requirements could deviate greatly from that. It is helpful to understand basal metabolic rate and total daily energy expenditure as well.
4. The fundamental principle of weight loss is to consume fewer calories than you burn. If you can appreciate this concept, then you can use your dietary and exercise level to control your weight.
5. Empty “calories” are calories that have little or no nutritional value. This generally means bad fats (trans and saturated) and sugars. Examples of so-called empty calories would include cupcakes and donuts, but there are many others.
6. Calories are an american description of units of energy. They are being replaced by joules and kilojoules, as this is the metric measurement of energy. These are not commonly included on food packaging in America, but you may see it abroad.